Add UMA for WebBluetooth RSSI signal strength level

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 93ea14f12ed4a018cc65c2f10994b2c3a7290c46..270bbc81b412769bec604afbce067b65df8eee5d 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -4760,6 +4760,29 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Bluetooth.Web.RequestDevice.RSSISignalStrength" units="dBm">
+  <owner>jyasskin@chromium.org</owner>
+  <owner>ortuno@chromium.org</owner>
+  <owner>scheib@chromium.org</owner>
+  <owner>juncai@chromium.org</owner>
+  <summary>
+    Raw RSSI values provided to chooser, before processing them for display in
+    the Web Bluetooth chooser.
+  </summary>
+</histogram>
+
+<histogram name="Bluetooth.Web.RequestDevice.RSSISignalStrengthLevel"
+    enum="WebBluetoothRSSISignalStrengthLevel">
+  <owner>jyasskin@chromium.org</owner>
+  <owner>ortuno@chromium.org</owner>
+  <owner>scheib@chromium.org</owner>
+  <owner>juncai@chromium.org</owner>
+  <summary>
+    Displayed RSSI levels, after processing and as displayed to users in the Web
+    Bluetooth chooser.
+  </summary>
+</histogram>
+
 <histogram name="Bluetooth.Web.RequestDevice.UnionOfServices.Count"
     units="services">
   <owner>jyasskin@chromium.org</owner>
@@ -103262,6 +103285,16 @@ value.
   <int value="18" label="Bluetooth Low Energy not available"/>
 </enum>
 
+<enum name="WebBluetoothRSSISignalStrengthLevel" type="int">
+  <int value="0" label="&lt;= minimum RSSI; displayed as level 0"/>
+  <int value="1" label="RSSI displayed as level 0"/>
+  <int value="2" label="RSSI displayed as level 1"/>
+  <int value="3" label="RSSI displayed as level 2"/>
+  <int value="4" label="RSSI displayed as level 3"/>
+  <int value="5" label="RSSI displayed as level 4"/>
+  <int value="6" label="&gt;= maximium RSSI; displayed as level 4"/>
+</enum>
+
 <enum name="WebCertVerifyAgreement" type="int">
   <int value="0" label="Accepted by both iOS and NSS."/>
   <int value="1" label="Rejected by both iOS and NSS."/>